JPH09156132A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize photographic printing according to a use with a simple printer by a method wherein a binary black head is used for character printing, and a two liquid mixing head is used for a full color image. SOLUTION: A printer head part is composed of a printer cartridge (two liquid mixing head) 25 wherein, for example, printer heads for yellow(Y), magenta(M), cyan(C), and black (B) of a two liquid mixing type are integrated into one body, a binary black head 26 made exchangeable with the printer cartridge 25, a carriage unit 28 which goes and comes back in an X main scan direction while mounting them, etc. Then, the printer cartridge 25 is made exchangeable with the binary black head 26 according to a photographic printing mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer such as a two-liquid mixing type (carrier jet) printer. More specifically, by making the printer head replaceable, full-color printing by two-liquid mixing and The present invention relates to an inkjet printer that realizes value-on-demand printing with a single printer.

[0002]

2. Description of the Related Art An on-demand type ink jet printer is a printer that ejects ink droplets from a nozzle in accordance with a control signal and deposits the ink droplets on a recording medium such as paper or film. It has become popular rapidly in recent years due to its potential for commercialization. The method of ejecting ink droplets from the nozzle includes a method of pressurizing the ink by displacement of the piezo element and a method of utilizing the pressure of bubbles generated by heating and vaporizing the ink in the nozzle by the heating element. Broadly divided. In principle, none of the methods can change the ink density immediately before the ejection, and therefore, it is not possible to express halftone density gradation in dot units on the recording medium.

On the other hand, in the office, document creation by a computer called desktop publishing has become popular, and there is an increasing demand for printing not only characters and figures but also color natural images such as photographs together with characters and figures. Even for personal use, such demand is great for New Year's cards and greeting cards. In order to print out a high-quality natural image, it is important to express gradation by displaying halftones.

As a method for solving the above-mentioned problems of the conventional on-demand type ink jet recording in principle, the applicant of the present invention mixes ink and a diluting liquid which is a transparent solvent at a predetermined mixing ratio immediately before jetting. An ink jet recording method (hereinafter simply referred to as "carrier jet method") in which a diluted ink is immediately ejected from a nozzle and adhered onto a recording medium has been developed.
It was disclosed in Japanese Patent No. 024. According to the carrier jet method, the density of ink is controlled for each droplet of ejected ink,
It is possible to freely express gradation for each dot on the recording medium. Therefore, it is possible to print out a natural image rich in halftones without deteriorating the resolution.

Such an ink jet printer has a printing mode such as a full color mode and a character printing mode. As an example, cyan (C), magenta (M),
Printing is performed using each of the yellow (Y) and black (Bk) printer heads. However, in the black (Bk) printer head, the binary liquid black (binary Bk) intended for characters is mixed with the above-described ink and diluent at a predetermined mixing ratio. (Two-component mixed Bk) was developed, and binary black was used for character printing and two-component mixed black was used for full-color images such as figures and photographs. Printing is required.

However, in the conventional ink jet printer, there is no provision for switching between the full-color printer head and the on-demand printer head according to the application, and full-color printing by two-liquid mixing and binary on-demand printing are performed. There is a problem that it is difficult to realize printing with a single printer.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and uses a binary black head for character printing and a two-liquid mixing head for full-color images. An object of the present invention is to provide an inkjet printer capable of printing according to various uses.

[0008]

SUMMARY OF THE INVENTION An ink jet printer of the present invention is proposed to solve the above-mentioned problems. It is possible to select a plurality of printing modes, and a recording medium and a printer based on an image signal. In an inkjet printer that forms a recorded image while performing main scanning and sub-scanning in two directions that are substantially orthogonal to the support to which the head is attached, the printer head can perform full-color printing according to each printing mode. The full-color printer head and the on-demand printer head capable of binary printing can be replaced. This makes it possible to select the printer head according to the content to be printed,
You can print in multiple print modes by simply changing the head used.

When the full-color printer head or the on-demand printer head is inserted, the contact portion of the full-color printer head is shared as the contact portion of the on-demand printer head. Therefore, the shared printer can be realized with the minimum number of contacts without increasing the number of contacts.

Since the full-color printer head and the on-demand printer head form images of different resolutions in the sub-scanning direction or in the main-scanning direction and the sub-scanning direction, for example, the full-color printer head is
With a resolution of 200 dpi suitable for full color printing,
The on-demand printer head is suitable for character printing 40
Images having different resolutions can be formed, for example, by having a resolution of 0 dpi.

In the ink jet printer, the type of the printer head is detected by a method of detecting the shape of the printer head by an optical sensor or mechanical means, the method of detecting a discrimination signal output to the contact portion of the printer head, A head type detecting means for detecting by at least one of the arbitrarily set methods is provided, and the printing mode is determined based on the detection signal generated by the head type detecting means. Therefore, switching of the head becomes easy,
The trouble of switching can be eliminated.

The circuit configuration of the ink jet printer includes a two-liquid mixing oscillator driving means for processing the full-color printer head and a binary black discharge driving means provided in parallel with the driving means for the on-demand printer head. And a switching means for switching these according to the printing mode. Further, it is provided with an ejection vibrator driving means for performing both processing of the full-color printer head and processing of the on-demand printer head. As a result, these output signals can be switched depending on the printing mode (full color printing / character printing), and the two-liquid mixing head / binary black head can be used with the minimum circuit configuration.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. First, the configuration of the inkjet printer of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a main configuration of an inkjet printer of the present invention.

As an example of the ink jet printer of the present invention, yellow (Y), magenta (M), cyan (C)
An example of a serial type color printer in which a plurality of printer heads of (1) are arranged on a line and black (Bk) printer heads are arranged on the same line to form an image will be described.

In FIG. 1, a recording paper 1 as a recording medium.
Are pressed and held on the drum by a paper pressure roller 3 provided in the axial direction of the drum 2. A feed screw 4 is provided on the outer periphery of the drum 2 in parallel with the drum axis direction, and the feed screw 4 holds a printer head unit 5 having a plurality of printer heads. The drum 2 is connected to a motor 9 via a pulley 6, a belt 7 and a pulley 8. The feed screw 4, the motor 9, and the printer head unit 5 are connected to the drive control unit 10, and the drive control unit 10 controls the control signal generation unit 1.
It is configured to be connected to 1.

The operation of the ink jet printer of the present invention thus constructed will be described.

The printer head unit 5 is moved forward or backward in the X main scanning direction by the rotation of the feed screw 4 to print one line or one scan. Then, the drum 2 is rotationally driven in the Y sub-scanning direction by one motor or N rows (in the case of interlaced scanning) by the motor 9 via the pulley 6, the belt 7, and the pulley 8 to print the next row. The feed screw 4, the motor 9, and the printer head unit 5 are controlled by a drive control unit 10, and the drive control unit 10 controls the control signal generation unit 11
It is controlled based on the print data and the control signal issued by the. The printer head unit 5 may be moved in the same direction or in the reciprocating direction.

Next, the structure of the printer head portion related to the ink jet printer of the present invention will be described with reference to FIG. FIG. 2 is a schematic sectional view of the printer head portion of the inkjet printer of the present invention.

The printer head section 5 is generally composed of three parts, an orifice plate 12, an ink container 13 and a diluting liquid container 14. The orifice plate 12 is provided with an ink supply port 15, a diluent supply port 16 and an ink flow path 17, and is obtained by mixing ink and diluent supplied from the ink supply port 15 and the diluent supply port 16. The nozzle 18 that ejects the diluted ink is opened. For example, the ink flow path 17 is formed in a tapered shape in which the width gradually narrows from the ink supply port 15 toward the nozzle 18.

Explaining the ink container 13 and the diluent container 14 connected to the orifice plate 12, the ink inlet 19 and the diluent inlet 20 are connected to a hollow ink reservoir 21 and a diluent reservoir 22, respectively. There is. These ink reservoir 21 and diluent reservoir 2
The other end of 2 is connected to the ink supply port 15 and the diluent supply port 16 of the orifice plate 12, respectively. On the outer wall surfaces of the ink container 13 and the diluting liquid container 14, an ink driving unit 23 and a diluting liquid driving unit 24 are arranged at positions facing the ink pool 21 and the diluting liquid pool 22. Ink drive unit 23 and diluent drive unit 24
Is formed of a bimorph piezoelectric element, but other driving means such as an electromagnetic conversion element or an electrostrictive element may be used.

Regarding the operation of the printer head section described above,
This will be described with reference to FIG.

In FIG. 2, the ink and the diluent, which are transported from a not-shown ink and diluent cartridge through the supply pipe, are supplied from the ink inlet 19 and the diluent inlet 20 to the ink container 13 and the diluent container 1.
4, the ink reservoir 21 and the diluting liquid reservoir 2 are introduced.
2 is filled.

The ink filled in the ink pool 21 is
Further, the ink flow path 17 is filled from the ink supply port 15,
A meniscus M is formed at the tip of the ink flow path 17 facing the nozzle 18 by a capillary phenomenon. Similarly, the diluting liquid filled in the diluting liquid reservoir 22 further fills the diluting liquid supply port 16, and the meniscus M is formed therein by the capillary phenomenon.

When printing is performed from this state, first, a pulse voltage is supplied to the ink drive unit 23 to supply ink to the ink container 1.
Stress is applied to the wall surface of No. 3 to increase the internal pressure of the ink reservoir 21. As a result, the ink in the ink flow path 17 moves in the direction of its tip, the tip of the meniscus M reaches the diluent supply port 16, and an ink droplet (not shown) is formed there.

Next, the diluent drive unit 24 of the diluent container 14
When a pulse voltage is applied to the nozzle, the internal pressure of the diluent reservoir 22 rises, the diluent ink (not shown) formed in the diluent supply port 16 moves toward the nozzle 18, and
8 is ejected as A ejection diluted ink. The jetted diluted A jetted ink becomes spherical due to surface tension and adheres to a recording medium (not shown). On the other hand, a meniscus M made of a new dilution liquid is formed again at the dilution liquid supply port 16 after the dilution ink is ejected. The above is the ejection operation of one cycle, and this cycle is sequentially repeated to form an image or the like on the recording medium.

Next, the structure of the printer head portion, which is a characteristic part of the present invention, will be described with reference to FIG. 3A and 3B are views showing an example of the printer head portion, FIG. 3A is an enlarged perspective view showing the printer head portion, and FIG. 3B is a rear view of the contact substrate of the printer head portion viewed from the wiring pattern side. is there.

The detailed structure of the printer head portion in FIG. 3A is, for example, a two-liquid mixed type yellow (Y).
Cartridge (two-component mixing head) 25 in which printer heads for magenta (M), cyan (C), and black (Bk) are integrated, and a binary black head 2 replaceable with the printer cartridge 25
6. A carriage unit 28, etc., on which these are mounted and which moves forward or backward in the X main scanning direction.

The printer cartridge 25 and the binary black head 26 are adapted to be connected to the contact portions 27 of the carriage unit 28 by connecting means (not shown), and the back surface of each of these heads is shown in FIG. As shown in FIG. 3, a flexible substrate (simply referred to as “FPC” in the figure) 30 having connection pads 29 is arranged. A probe pin (not shown) is arranged at the contact portion 27 of the carriage unit 28, and the flexible substrate 30
The connection pad 29 is connected to the probe pin of the carriage unit 28.

The structure of the printer head unit 5 is a diagram schematically shown for easy understanding, and actually the drive I
It may be formed together with C. Although not shown, for example, a printer cartridge (two-liquid mixing head) 2
5 has a resolution of 200 dpi, which is suitable for full-color printing, and the binary black head is 400 d, which is suitable for character printing.
It can also be configured with a resolution of pi. Thereby, images with different resolutions can be formed.

Further, the printer cartridge 25 has exemplified the example in which the printer heads for yellow (Y), magenta (M), cyan (C) and black (Bk) are integrated, but these printer heads are respectively used. In some cases, it may be configured as a single body, or in which yellow (Y), magenta (M), and cyan (C) are integrated, and only the black (Bk) head is configured independently. In this case, only the two-liquid mixed black (Bk) head can be replaced with the binary black head. The present invention is not limited to the structure and operation of the printer head.

The circuit configuration of the above-mentioned ink jet printer will be described with reference to FIG. FIG. 4 is a block circuit diagram showing the inkjet printer of the present invention.

The circuit configuration of the ink jet printer of the present invention comprises a CPU system bus B connected to the CPU 31,
A print data processing unit 32 that processes print data input from a data input interface unit (not shown) and the like, and a timing control unit 3 that generates and controls various timing signals.
3, a two-liquid mixing oscillator driving unit 34 that controls the mixing oscillator of the two-liquid mixing head, a binary black ejection oscillator driving unit 35 that controls the ejection oscillator of the binary black head, and a diluting liquid of the two-liquid mixing head And the like, and a "two-liquid mixing operation signal" connected to the ejection vibrator driving unit 36, the driver unit 37, and the CPU system bus B that controls half of the ejection vibrators of the binary black head and the like. Mixing / ejection switching section 38 as switching means for switching the vibrator drive section 34 or the binary black ejection vibrator drive section 35, the driver section 39, the contact section 27, and the two-liquid mixing / binary Bk head 40. And a head type detecting means 41 for detecting the type of these heads and issuing a "head type detection signal" to the CPU system bus B.

The circuit operation of the ink jet printer thus configured will be described.

When the user of the ink jet printer starts printing, a print start command is input via a data input interface section (not shown) and the print start request command is sent via the CPU system bus B. Sent to the CPU 31. The CPU 31 starts processing necessary for printing the image data based on the program data stored in the ROM (not shown), and replaces the image data with the printing data for printing. The print data processing unit 32 receives the print data together with the timing signal generated by the timing control unit 33, and as the print data, the two-liquid mixing vibrator driving unit 34, the binary black ejection vibrator driving unit 35, and the discharge vibrator driving unit 36. Supply to each.

The two-liquid mixing vibrator driving section 34 generates a driving signal for the two-liquid mixing vibrator based on the printing data input from the printing data processing section 32. The binary black ejection oscillator drive unit 35 generates drive signals for half the number of binary black ejection oscillators based on the print data input from the print data processing unit 32. In the ejection oscillator drive unit 36,
When a two-liquid mixing head is used, a diluting liquid or the like is ejected based on the print range setting, and when a binary black head is used, the print data input from the print data processing unit 32 is used. Based on this, drive signals for the other half of the binary black ejection oscillator are generated.

The mixing / ejection switching section 38 switches the drive signal of the two-liquid mixing oscillator or the binary black ejection oscillator based on the "two-liquid mixing operation signal" issued from the CPU 31 via the CPU system bus B. Output. The driver units 37 and 39 amplify the electric power necessary for displacing the electrostrictive oscillator of the printer head, and output it to the two-liquid mixing / binary Bk head 40 as an applied signal. Two liquid mixture /
In the binary Bk head 40, the electrostrictive oscillator is displaced according to the voltage level of the applied signal as described above to increase the internal pressures of the ink pool and the diluting liquid pool, and when the two-liquid mixing head is used, the amount of ink is determined and The quantified ink and the diluting liquid are mixed and ejected from the nozzle as A jetting diluting ink. In addition, when the binary black head is used, ink is ejected from the nozzle.

Further, details of the head portion of the ink jet printer of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing the configuration of the head portion of the inkjet printer of the present invention, in which (a) is an operation example when a two-liquid mixing head is used,
(B) is an explanatory view showing an operation example when using the binary black head.

The difference in structure between the binary liquid mixing head and the binary black head is that the binary liquid mixing head mixes the ink and the diluent in the vicinity of the nozzle, whereas the binary black head uses the ink from both nozzles. The main difference is that the discharge is performed. In this example, as shown in FIG. 5, the ejection oscillator 36a is shared by the two-liquid mixing head and the binary black head. Therefore, the binary liquid mixing head and the binary black head can be used together simply by changing the signal waveforms and the timings applied to the binary liquid mixing oscillator 34a and the binary black ejection oscillator 35a. Also, the resolution in the sub-scanning direction is doubled with the two-liquid mixing head and the binary black head, and the resolution in the main scanning direction can be doubled by doubling the drive frequency during the main scanning. Becomes Of course, the data processing method before each drive unit is largely different between the two-liquid mixing head and the binary black head. Hereinafter, the circuit operation of the head unit is as described above.

Returning to the explanation of FIG. 4, the head type detecting means 41 determines the type of the printer head, for example, the following three types.
Recognized by the method, CP as "head type detection signal"
The data is sent to the U system bus B, and the CPU 31 determines and determines the operation mode.

First, the outer shape of a part of the full-color printer head or the on-demand printer head is changed, and the shape is detected by an optical means such as a photo sensor and a mechanical means such as a tact switch. As the second, the type of the printer cartridge, for example, "1",
A terminal for detecting "0" is provided, and the type of the printer head is detected by detecting the discrimination signal.
As the third, it is conceivable that the user of the inkjet printer sets the desired type of printer head by operating and inputting it by software using a switch element or a command.

The print data processing unit 32 has a built-in correction circuit (not shown), and performs γ correction, color correction in the case of a color printer, dispersion correction of each head, and the like. It is common to store predetermined correction data in a ROM map format in the correction circuit and retrieve it according to external conditions such as nozzle number, temperature, and input signal. It should be noted that the head circuit portion indicated by the broken line indicates the circuit of the pair of printer heads, and actually there are as many nozzles as there are heads. Further, since the description of the mechanism system such as head feeding overlaps, the description thereof will be omitted.

According to such a carrier jet type ink jet printer, in addition to the two-liquid mixing oscillator driving unit 34, in parallel therewith, the binary black ejection oscillator driving unit 35.
The output signals are switched depending on the printing mode (full-color printing / character printing), etc., and the discharge vibrator driving means is shared, so that a two-liquid mixing / binary Bk head can be used with a minimum circuit configuration. can do. As a result, it is possible to print out an image with high-speed and accurate gradation expression.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. As a recording method of the printer, other than the two-liquid mixing method (carrier jet printer) exemplified in this embodiment, an inkjet printer of a method of heating and vaporizing ink by a heating element and ejecting the ink, a binary inkjet printer, a dot diameter modulation method It goes without saying that the present invention can be applied to various color printers such as an inkjet printer and a density modulation type inkjet printer. Further, it goes without saying that the present invention is not limited to the above-described embodiment and can be developed into various forms.

[0044]

As is clear from the above description, according to the ink jet printer of the present invention, the printer head includes a full-color printer head capable of full-color printing and an on-demand printer head capable of binary printing. Since it is possible to replace according to the print mode, it is possible to select the optimum printer head according to the content to be printed, and it is possible to print different print modes with a single printer simply by changing the used head. Become.

In the ink jet printer according to the second aspect of the present invention, when the full-color printer head or the on-demand printer head is inserted into the printer, the contact portions are shared, so that the minimum number of contact points can be shared without increasing the number of contact points. It becomes possible to realize a printer.

In the ink jet printer according to the third and fourth aspects, the full-color printer head and the on-demand printer head form images of different resolutions in the sub-scanning direction or the main scanning direction and the sub-scanning direction. Without changing the driving method of
It is possible to form images with different resolutions.

In an ink jet printer according to a seventh aspect, a two-liquid mixing oscillator driving unit for performing processing of a full-color printer head, a binary black ejection oscillator driving unit for performing processing of an on-demand printer head, and these The switching means for switching the printing mode according to the printing mode (full-color printing / character printing) and the ejection vibrator driving means are also provided so as to be shared. As a result, it is possible to use the two-liquid mixing head and the binary black head with the minimum circuit configuration.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main configuration of an inkjet printer of the present invention.

FIG. 2 is a schematic sectional view of a printer head portion of the inkjet printer of the present invention.

3A and 3B are views showing an example of a printer head portion of the inkjet printer of the present invention, FIG. 3A is an enlarged perspective view of the printer head portion, and FIG. 3B is a wiring pattern of a contact substrate of the printer head portion. It is the rear view seen from the side.

FIG. 4 is a block circuit diagram showing an inkjet printer of the present invention.

5A and 5B are diagrams showing a configuration of a head portion of the inkjet printer of the present invention, FIG. 5A is an explanatory diagram showing an operation example when a two-liquid mixing head is used, and FIG. 5B is an operation when a binary black head is used. It is explanatory drawing which shows an example.

[Explanation of symbols]

 1 Recording Paper 2 Drum 3 Paper Pressing Roller 4 Feed Screw 5 Printer Head Section 6, 8 Pulley 7 Belt 9 Motor 10 Drive Control Section 11 Control Signal Generation Section 12 Orifice Plate 13 Ink Container 14 Diluent Container 15 Ink Supply Port 16 Diluting Solution Supply port 17 Ink flow path 18 Nozzle 19 Ink introduction port 20 Diluent introduction port 21 Ink pool 22 Diluting liquid pool 23 Ink drive unit 24 Diluent drive unit 25 Printer cartridge 26 Binary black head 27 Contact point unit 28 Carriage unit 29 Connection pad 30 flexible substrate 31 CPU 32 print data processing unit 33 timing control unit 34 two-liquid mixing oscillator driving unit 35 binary black ejection oscillator driving unit 36 ejection oscillator driving unit 37, 39 driver unit 38 mixing / ejection switching unit 40 two Liquid mixing / binary B k head 41 head type detection means

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 16, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

Such an ink jet printer has a printing mode such as a full color mode and a character printing mode. As an example, cyan (C), magenta (M),
Printing is performed using each of the yellow (Y) and black (Bk) printer heads. However, in the printer head of black (Bk), with respect to the binary black shall be the object of a character (binary Bk), two-part mixing black mixing the diluent and ink as described above at a predetermined mixing ratio (Two-component mixed Bk) was developed, and binary black was used for character printing and two-component mixed black was used for full-color images such as figures and photographs. Printing is required.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The printer head unit 5 is moved forward or backward in the X main scanning direction by the rotation of the feed screw 4 to print one line or one scan. After that, the drum 2 is rotationally driven in the Y sub-scanning direction by one motor or N lines (in the case of interlaced scanning) in the Y sub-scanning direction by the motor 9 via the pulley 6, the belt 7, and the pulley 8, and the next line or the next line is driven. Print. Feed screw 4, motor 9 and printer head unit 5
Is controlled by the drive control unit 10, and the drive control unit 10
Are controlled based on the print data and the control signal generated by the control signal generator 11. The printer head unit 5 may be moved in the same direction or in the reciprocating direction.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04N 1/23 101

Claims (7)

[Claims] 1. A recorded image having a plurality of printing modes and performing main scanning and sub-scanning in two directions substantially orthogonal between a recording medium and a support to which a printer head is attached, based on an image signal. In the inkjet printer for forming a printer, the printer head includes a full-color printer head capable of full-color printing and an on-demand printer head capable of binary printing.
An ink jet printer characterized by being exchangeable according to the printing mode. 2. A contact portion of the full-color printer head is shared as a contact portion of the on-demand printer head when the full-color printer head or the on-demand printer head is inserted. Item 2. The inkjet printer according to Item 1. 3. The ink jet printer according to claim 1, wherein the full-color printer head and the on-demand printer head form images of different resolutions in the sub-scanning direction. 4. The inkjet printer according to claim 1, wherein the full-color printer head and the on-demand printer head form images having different resolutions in the main scanning direction and the sub-scanning direction. 5. The ink jet printer comprises head type detection means for detecting the type of the printer head, and determines the printing mode based on a detection signal generated by the head type detection means. The inkjet printer according to claim 1. 6. The detecting means of the head type detecting means,
At least one of a method of detecting the shape of the printer head, a method of detecting a discrimination signal output to a contact portion of the printer head, and a method arbitrarily set by a user. Item 5. The inkjet printer according to Item 5. 7. A two-liquid mixing oscillator driving unit for performing processing of the full-color printer head, and a two-component mixing unit provided in parallel with the two-liquid mixing oscillator driving unit for performing processing of the on-demand printer head. Value black discharge driving means, switching means for switching the two-liquid mixing oscillator driving means and the binary black discharge driving means in accordance with the printing mode, output of the switching means, processing of the full-color printer head, or An ejection oscillator driving unit for performing the processing of the on-demand printer head, the two-liquid mixing oscillator driving unit and the binary black ejection driving unit are switched by the switching unit, and the ejection oscillator driving unit is shared. Thus, both printer heads can be driven with a minimum circuit configuration. Ink jet printer.